Surface maintenance machine

ABSTRACT

A surface maintenance machine having a scrubber head unit, a power drive unit that includes a dirty solution tank, a cleaning solution tank, a removable operator&#39;&#39;s seat whereby the machine may be used as an operator ride-on unit or a walk-behind unit, and a parallel linkage system for moving the scrubber unit between the elevations: (1) A horizontal cleaning position, (2) A horizontal transport position, and (3) An elevated turning position, and in the third position permitting the scrubber head unit being rotated about 90* to a generally vertical position, and lock mechanism to releasably retain the scrubber head unit in either of positions (2) and (3), or the vertical condition, and a propelling steerable front wheel having a brake resiliently retained in a braking condition and a rear squeegee assembly at the rear of the power unit. The scrubber head unit in a horizontal condition is of a substantially greater width than the maximum width of the power unit and about the same width as the rear squeegee assembly which is easily removable, while the height of the scrubber unit in a horizontal position is substantially less than the maximum width of the power unit. The scrubber head unit includes a pair of easily removable, power driven rotatable brushes, a squeegee assembly, and a combination baffle-trough that may be selectively mounted to collect liquid and debris raised by the brushes, or to permit the raised liquid to be recirculated to the surface being cleaned.

- States Patent Fortrnan et al.

[ SURFACE MAINTENANCE MACHINE [75] Inventors: Lloyd D. Fortman; Joseph G.

' Kasper, both of Golden Valley,

Minn.

[73] Assignee:- Tennant Company, Minneapolis,

Minn.

[22] Filed: Sept. 25, 1972 [21] Appl. No.: 292,182

Primary Examiner-Harvey C. Hornsby Assistant ExaminerChristopher K. Moore Attorney, Agent, or Firm-Bugger, Johnson & Westman [57] ABSTRACT A surface maintenance machine having a scrubber 1451 Sept. 10, 1974 head unit, a power drive unit that includes a dirty solution tank, a cleaning solution tank, a removable operators seat whereby the machine may be used as an operator ride-on unit or a walk-behind unit, and a parallel linkage system for moving the scrubber unit between the elevations: (l) A horizontal cleaning position, (2) A horizontal transport position, and (3) An elevated turning position, and in the third position permitting the scrubber head unit being rotated about 90 to a generally vertical position, and lock mechanism to releasably retain the scrubber head unit in either of positions (2) and (3), or the vertical condition, and a propelling steerable front wheel having a brake resiliently retained in a braking condition and a rear squeegee assembly at the rearof the power unit. The scrubber head unit in a horizontal condition is of a substantially greater width than the maximum width of the power unit and about the same width as the rear squeegee assembly which is easily removable, while the height of the scrubber unit in a horizontal position is substantially less than the maximum width of the power unit. The scrubber head unit includes a pair of easily removable, power driven rotatable brushes, a squeegee assembly, and a combination baffle-trough that may be selectively mounted to collect liquid and debris raised by the brushes, or to permit the raised liquid to be recirculated to the surface being cleaned.

28 Claims, 17 Drawing Figures PAIENIED sEP 101924 I amass-1 SHEET 10f 8 PATENTED SEP 1 01974 SHEET 0F 8 Fi I535 PAIENIEUsEH 0:914

SHEET 7 OF 8 T'ANK FILTER L228 ADJUSTABLE 238a. PILOT a ex/1150 VALVE ELECTRIC BRAKE CYL.

PATENTEDSEPIOIQH imam snsns or e 1 SURFACE NTENANCE MACHINE BACKGROUND OF THE INVENTION A surface cleaning machine for scrubbing surfaces that includes a power unit and a scrubber head unit movable to various positions relative the power unit.

With prior art power driven surface cleaning machines there is a problem that the width of the scrubbing head unit is limited by the width of the doorways or other narrow passageways that the machine has to be moved through in order to travel to the area to be cleaned. Also prior art machines are not readily adapted for use as operator ride-on unit or a walk-. behind unit without the attachment of such as a sulky.

Additionally the scrubbing brushes are not readily removable unless the strength of the construction of the brush housing side walls is unduly scarificed by the provision of such as a side door. In order to overcome problems such as the above, as well as others, this invention has been made.

SUMMARY OF THE INVENTION A surface cleaning machine having a power drive unit and a scrubber head unit that includes a power driven rotary tool, the power drive unit including a parallel linkage assembly for moving the scrubber head unit in a generally horizontal condition between a surface cleaning position and an elevated turning position, the linkage assembly including a pivot assembly for mounting the scrubber head unit for pivotal movement, when in the elevated position, to a generally vertical position, and lock mechanism for selectively retaining the scrubber head unit in a generally horizontal position and a generally vertical position.

One of the objects of this invention is to provide a surface cleaning machine having a mobile power unit and a surface cleaning unit that includes a rotary brush with a new and novel mounting assembly for mounting the surface cleaning unit on the power unit for movement between various selected positions relative the surface being cleaned. In furtherance of the above object; it is another object of this invention to provide a mounting assembly for mounting the cleaning unit for rotation through an angle of 90 about a horizontal axis from a generally horizontal condition to a generally vertical condition and selectively retaining the surface cleaning unit in either of said conditions. With reference to the above objects, it is a further object of this invention to provide a mounting assembly having new and novel mounting members for mounting the surface cleaning unit for movement between laterally offset positions relative the power unit.

Still another object of this invention is to provide a surface cleaning unit having a new and novel mounting of a rotary brush to permit the easy removal thereof. A further object of this invention is to provide in a surface scrubbing unit having a rotary brush, a new and novel combination baffledebris hopper that may be used for collecting liquid and debris raised by the brush and alternately aid in returning liquid raised by the brush to the surface.

Another object of this invention is to provide a scrubbing unit with a squeegee assembly having a new and novel mounting of the squeegee. An additional object of this invention is to provide a surface cleaning machine with a squeegee assembly of a new and novel construction, and new and novel structure for mounting the squeegee assembly for limited vertical movement.

A further object of this invention is to provide a surface cleaning machine having a power driven steerable wheel with a new and novel brake assembly that is constantly urged to a braking condition. An additional object of this invention is provide a surface cleaning machine having an electric motor driven pump with a new and novel mounting of the motor to facilitate performing maintenance operations on the motor.

An additionalobject of this invention is to incorporate new and novel safety features into a surface maintenance machine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a right side view of the surface maintenance machine of this invention, said view showing the scrubbing unit in its normal, horizontal surface scrubbing position in solid lines, the clean liquid tank in its normal position in solid lines and in a hinged forward position permitting access to the batteries and other structure therebeneath in dotted lines, and two different positions of the scrubber head unit in dotted lines, the lowermost dotted line position being a transport position and the uppermost dotted line position being an elevated turning position permitting the scrubber head turning about a horizontal axis to a vertical positron;

FIG. 2 is a front view of the apparatus of FIG. 1, the solid line and the two dotted line positions of the scrubber head unit of FIG. 1 being illustrated and a third dotted line position of the scrubber unit also being illustrated, the third dotted line position being a vertical position turned 90 relative the other positions, portions of the scrubber unit being broken away to illustrate other structure thereof;

FIG. 3 is a perspective view of the lift assembly for mounting the scrubber unit and moving the scrubber unit between its various positions and the latch mechanism for selectively retaining the scrubber unit in two of its positions, said view showing the lift assembly and latch mechanism in a scrubber unit transport position in solid lines, and in dotted lines, showing the latch mechanism in the scrubber unit elevated turning positron;

FIG. 4 is a longitudinal cross-sectional view of the scrubber unit with the combination collection troughbaffle shown in a position for collecting debris raised by the brushes;

FIG. 5 is a fragmentary, vertical transverse crosssectional view generally taken along the line and in the direction of the arrows 5-5 of FIG. 7 to show the mounting of one end portion of a rotary brush;

FIG. 6 is a fragmentary cross-sectional view generally taken along the line and in the direction of the arrows 66 of FIG. 8 to more clearly illustrate the mounting of the scrubber unit squeegee;

FIG. 7 is a fragmentary cross-sectional view generally taken along the line and in the direction of the arrows 77 of FIG. 5 to show the mounting a brush;

FIG. 8 is a fragmentary view of the rear portion of the scrubber unit with portions being broken away to more clearly illustrate the mechanism for releasably retaining the scrubber head unit in generally horizontal condition and showing the combination baffle-debris hopper in a position that the raised debris and liquid is recycled to the surface being scrubbed; 1

FIG. 9 is a fragmentary plan view illustrating the mounting of the electric motor in driving relation to a hydraulic pump, in solid lines, portions thereof being broken away, and the electric motor being shown in a hinged dotted line position to facilitate performing maintenance thereon;

FIG. 10 is a fragmentary view illustrating the lock mechanism for releasably retaining the scrubber unit in a generally vertical condition;

FIG. 11 is a schematic diagram illustrating the hydraulic components and controls of the apparatus of this invention;

FIG. 12 is a side view of the front wheel mounting and brake structure, portions being broken away;

FIG. 13 is a fragmentary vertical, cross-sectional view of the structure of FIG. 12;

FIG. 14 is an enlarged fragmentary view more clearly illustrating the cam and adjacent ends of the brake shoe of FIG. 12;

FIG. 15 is a fragmentary view of a modified embodiment of the mounting of the scrubber unit to permit laterally displacing the scrubber unit relative the power unit;

FIG. 16 is a fragmentary, vertical cross-sectional view of the scrubber head mounting structure of FIG. 15; and

FIG. 17 is a fragmentary top view showing the battery compartment and adjacent structure, part diagrammatically and the cleaning solution tank being broken away.

Referring now to the drawings there is illustrated a surface cleaning machine, generally designated 10 that includes a power and drive unit, generally designated 11, and a scrubber head unit, generally designated 12, that is mounted on the unit 11 to extend forwardly thereof. The power unit 11 includes a main frame 13 that mounts transversely spaced rear wheels 15 and a front steerable and drive wheel assembly, generally designated 14, that is connected through a suitable steering linkage (not shown) to the steering wheel 16 that extends rearwardly of the main frame such as shown in FIG. 1. Since the structure of the steerable wheel assembly 14, including the mounting thereof, may be similar to that described in U.S. Pat. No. 3,604,051, granted Sept. 14, 1971, which discloses the mounting of a rear steerable wheel, the manner of mounting the front wheel assembly for steerable movement will not be described.

Mounted on the main frame to extend rearwardly thereof, are a pair of longitudinal, transversely spaced frame members 18 that mount the depending legs of a generally U-shaped frame member 19. The frame member 19 has a top, transversely extending, web portion that is provided with a plurality of transversely spaced bolt openings (not shown). A longitudinally extending seat support bar 21 has a front clevised bracket with transversely spaced bolt openings to permit the seat being secured to the web of frame member 19 in transversely spaced adusted positions by bolts 22. Further, by removing all except one bolt 22, the frame member 21 may be pivoted about a vertical axis of the remaining bolt so that the bar 21 extends generally transversely of the machine with the seat 25 off to one side of the machine. An upright support 24 is mounted on the intermediate portion of the bar 21 to in turn I mount the operator seat 25, a stop plate 26 being mounted on the support bar 21 rearwardly of the seat to abut against a vertical wall in the event the operator while sitting on the seat backs up too far. Since the steering wheel 16 is at an elevation to be turned by an operator standing on the surface being cleaned, or sitting on the seat, the machine 10 may be used as either a walk-behind scrubber, or an operator ride-on scrubber.

Mounted on the upper rear portion of the power unit frame is a dirty liquid tank 29 having a plenum chamber portion 30 opening to the top thereof. Removably mounted on the top wall of the plenum chamber to have the inlet thereof open to the plenum chamber is a suction blower 31 for applying a vacuum to the plenum chamber. Extending into the tank 29 and opening into the interior thereof adjacent the plenum chamber is a fluid conduit 33, a scrubber unit squeegee conduit 34, and a collection trough conduit 35. Each part of the conduit that extends outwardly of the dirty liquid tank is of a flexible nature, the lower end portion of the conduit 33 being connected to a suitable take-up tube 36 of the rear squeegee assembly, generally designated 37. Each conduit includes a tube extending within the tank, the conduits being sized for the application of the proper vacuum at the members connected to the inlet ends of the conduits. The rear squeegee assembly is located rearwardly of the rear wheels and advantageously is of about the same width as the surface maintenance unit 12. The squeegee assembly 37 includes a squeegee frame 41 and a pair of transversely spaced upright brackets 38 secured thereto, each bracket having a one end portion of the longitudinally elongated rod 39 loosely extended therethrough. A readily removable pin (not shown) is extended through the rear end portion of each rod 39 for removably retaining the bracket on the rod. Each rod 39 extends forwardly to have its forward end portion mounted on the main frame adjacent the front end of the power unit. As may be noted from FIG. 1, the rods 39 are of longer lengths than the longitudinal spacing between the front and rear wheels. As a result of the relatively long lengths of the rods 39, the squeegee assembly 37 in being moved from an elevated position to a surface engaging position moves through a sufficiently large radius of curvature that it is not necessary to use a complicated linkage having a plurality of pivots mounting or forming part of the squeegee assembly. Further, the rear squeegee assembly has limited rocking action so that it can move to follow uneven surfaces being cleaned. It is to be noted that the squeegee assembly may be retained in an elevated condition by suitable means, for example, a chain (not shown).

Mounted on the power unit frame forwardly of the dirty liquid tank is a cleaning solution tank 42. The tank 42 is hingedly connected along its front lower edge at 43 to the main frame to permit it being pivoted from its datum position rearwardly of the scrubbing unit to the dotted line position of FIG. 1 in overlaying relationship to the scrubbing head unit to permit access to components positioned under the clean liquid tank in its datum position. Also a shroud 42a is mounted on the power unit frame by hinges 42b that have a hinge axis adjacent and parallel to the tank hinge, the shroud being pivotable to a position extending over the tank.

In order to mount the scrubber head unit 12 for movement between the generally horizontal positions: (1) scrubbing position, (2) transport position (dotted line positions 12b of FIGS. 1 and 2), and (3) an elevated turning position (dotted line positions 12c of FIGS. 1 and 2), and a generally vertical position (dotted line position 12d of FIG. 2), there is provided the scrubber head mounting assembly (lift assembly) generally designated 46, see FIGS. 1-3. The assembly 46 includes a transverse shaft 47 that is pivotally mounted in a fixed position by the main frame, the rear end of upper parallel arms 48 being secured to the shaft to rotate therewith. The forward ends of arms 48 are each pivotally connected at 49 to the upper end of a vertical bar 50 while the lower end of each bar 50 is pivotally connected at 51 to the front end of a lower arm 52. The rear end of each arm 52 is pivotally connected to the frame 13 by a pivot member 53 while the upper intermediate portions of the bars 50 mount a transverse channel (support member) 54 which extends therebetween to move therewith. Through the aforementioned structure, the bars 50 are retained in a vertical condition as the parallel links 48, 52 are pivoted about shaft and pivot members 47, 53 respectively. In order to pivot the parallel links 48, 52, the one end of a cylinder 58 of a piston/cylinder combination 58, 59 is pivotally connected at 60 to main frame portion 11a while the piston rod 59 is pivotally connected at 61 to radial arms 62 which are in turn welded to the shaft 47.

Welded to the support member 54 to be located substantially more closely adjacent the right hand bar 50 than the left hand bar 50 as viewed in FIG. 3, is a shaft mount 64 that mounts the rear end portion of a shaft 65 that has a central longitudinally extending pivot axis. A transverse channel (support member or frame member) 66 of the scrubber head unit 12 is pivotally mounted on the front end portion of shaft 65 to pivot about the central axis of said shaft. Through the aforementioned structure, the central axis of shaft 65 is retained in a generally horizontal, longitudinally extending condition even though the elevation thereof is varied through the operation of the piston/cylinder combination 58, 59. Further the support member 54 is mounted to extend forwardly of the main frame of the power unit while the shaft 65 extends forwardly of the support member 54. Accordingly the scrubber unit may be moved between its positions without engaging the main frame.

In order to releasably retain the scrubber head unit in either the transport position or the elevated turn position, there is provided the latch mechanism, generally designated 70 (see FIGS. 2 and 3). The latch mechanism includes a latch plate 71 having a lower end portion pivotally connected at 72 to main frame portion 11b while the lower corner portion of the latch plate pivotally mounts the one end of a link 73. The opposite end of link 73 is pivotally connected to a radial arm 74 that is fixedly secured to a rod 75 t'o-rotate therewith. The opposite end of the rod 75 is suitably connected to a foot operated pedal (not shown) at the lower rear of the drive unit to move the plate 71 between the positions indicated hereinafter, and to limit the pivotal movement of the plate in a direction opposite arrow 77. A coil spring has one end attached to plate 71 on the side of pivot opposite the connection of link 73 and a lower end connected to frame portion 11b. The plate 71 is provided with a notch that in a plate datum position, provides a generally horizontal surface 711) on the opposite side of the pivot 72 from which the linkage 73 is connected to the plate. The edge 71b is located intermediate the inclined top edge 71a of the notch and the inclined lower edge 71e of plate 71, the plate having a top edge 710. When the foot pedal (not shown) is operated to pivot the plate 71 from its datum dotted line position of FIG. 2 in the direction of the arrow 77 about pivot member 72, the plate is moved out of the path of movement of the bars 48, 52 (see solid line position of FIG. 2) assuming arm 48 was above one of edges 7lb, 71;. At this time the piston/cylinder combination may be operated to pivot bars 48 in the appropriate direction to move the scrubber head to its lowermost position, whereby the arm 48 would be below the edge 71e and then the foot pedal released whereupon spring 80 returns the plate 71 to its dotted line position of FIG. 2. Now upon operating the piston/cylinder combination to pivot the arm 48 in the direction of the arrow 78, the adjacent arm 48 abuts against the edge 71e of plate 71, which is inclined upwardly to the right side of the machine, to cam the plate in the direction of the arrow 77 about pivot 72, and upon being raised to an elevation above edge 71b, the coil spring 80 will pivot the plate to a position in which edge 71b underlies arm 48. If the application of fluid under pressure to cylinder 58 is discontinued, the arm 48 will lodge on edge 71b to prevent the arm pivoting in the direction opposite arrow 78 about shaft 47 and will retain the scrubber head unit in its transport position. However, if the application of fluid under pressure to cylinder 48 is continued, the arm 48 in moving above the elevation of edge 7lb will abut against the diagonally upwardly inclined edge 71d of the plate to cam the plate out of the path of movement of said arm 48 until the arm is above edge 710. At this time spring 80 returns plate 71 to the position that edge 71c underlies the adjacent arm 48, and if the application of fluid under pressure to cylinder 58 is discontinued, the arm 48 will abut against edge 710 to retain the scrubber head unit in its elevated turning position. With reference to the above, the coil spring 80 constantly resiliently urges the plate to its solid line position of FIG. 2 and will return it to such a position, providing the adjacent arm 48 is not in the path of movement of the plate and sufficient pressure is not being applied to the foot pedal. The edge 71e is inclined such that the adjacent arm 52 will not abut against plate 71, even when the parallel linkage is operated to move the scrubber head unit to maximum elevation by combination 58, 59. A detent (not shown) is provided on the plate 71 to selectively retain the foot pedal in a position that plate 71 is held out of the path of movement of the arms of the parallel linkage.

The scrubber head unit 12 includes a housing having side walls 85, 86 that are fixedly secured to the opposite ends of the channel (support member) 66 (see FIGS. 4, 7 and 8). A front wall panel 87 of about half of the height of the side walls extends between and is secured to said side walls. The front edge of a deflector 88 is secured to the upper edge of the panel 87, the deflector having side edges secured to the adjacent side wall and a rear edge secured to an intermediate panel 89 that has a main body portion 89a inclined upwardly forwardly. A door 91 is hingedly connected at 92 to the upper edge of the front panel and extends in overlying relationship to the top flange 89b of panel 89 to in conjunction with the portions of side walls 85, 86, panel 89 and deflector 88, form an enclosed chamber 93. Further, the housing includes a top rear panel 96 that has opposite edges mounted by the side walls and has a front flange 96a that is substantially spaced from and parallel to the main body 890 of panel 89. Portions 96a, 89b and the side walls form an upwardly opening 97 in the housing through which the combination baffle hopper, generally designated 100 may be removed. Additionally the housing includes a bottom channel 101 that extends between and has its end edges secured to the side walls, channel 101 including a generally rectangular bottom wall 101a forming a web portion of the channel, a rear leg 101b and a front leg 1016 that extends in substantially the same plane as panel portion 890. The top edge of portion 101C together with the edge formed at the juncture of deflector 88 and panel portion 89a in part define an opening 102 through which debris may pass as described hereinafter.

The baffle hopper combination 100 includes a hopper having a top wall 103, side walls 104, a bottom wall 105, a rear wall 106 and a front wall 107 that are joined together to form an enclosed hopper other than for the front opening that in a debris collecting condition opens to opening 102, and the top opening through which the liquid take-up tube 110 is extended. In this connection, it is to be noted that the bottom wall of the trough formed by walls 105, 107 and portions of walls 104, 106 bears against web portion 101a of the channel 101 while wall portion 107 is closely adjacent channel portion 101C.

The upper end portion of the take-up tube 110 is above the top wall 103 when the trough is in the FIG. 4 position and is removably connected to the vacuum hose 35, the opposite end of the take-up tube being located closely adjacent the bottom wall and opening into the interior of the trough. The inlet end of tube opens into the interior of tubular screen 111 that is of a substantially larger diameter than the tube 110 and is an axial length to extend substantially the transverse width of the trough. The screen is closed at either end and provides a large filter for screening out material that would otherwise block the inlet end of tube 110.

Housing portions 101C, 87, 88 and the adjacent portions of side walls 85 and 86 cooperatively form a downwardly opening brush chamber 115 that is enclosed other than for the bottom opening and the opening 102, and the cleaning solution inlet opening that will be referred to hereinafter. Mounted in the brush chamber for rotation about transverse, parallel horizontal axes are tubular brushes (rotary surface maintenance tools) 118, 119, the brushes extending below the lower edges of the scrubber unit housing. The rear brush 118 has a peripheral rear portion closely adjacent opening 102 such as shown in FIG. 4; while the deflector 88 has a depending apex edge 88a that is in an overhanging relationship to the rear peripheral portion of front brush 119, apex edge 88a extending parallel to the axis of rotation of the brushes. Preferably the brushes are counterrotating with the surface engaging parts of the brushes rotating toward one another.

In order to drive the brushes, the hydraulic motor 121 is mounted on side wall 86 within chamber 93 and has a motor shaft 122 extending outwardly of the side wall to have a sprocket 124 keyed thereto. A chain 125 is extended over sprocket 124, partially around an idler sprocket 126, thence in engagement with the sprocket 127, thereafter partially around sprocket 128 and thence back to sprocket 124. Since the underside of the lower run of the chain abuts against sprocket 127 and the upper side (opposite side) of the lower run bears against sprocket 128, as the chain is driven, sprockets 127, 128 are rotated in opposite angular directions. Sprockets 125, 127 and 128 are mounted for rotation about parallel axes by side wall 86 exterior of the brush chamber. Each of sprockets 127, 128 is pinned to a stub shaft 130 that extends through and is mounted by side wall 86. Pinned to each shaft 130 is a brush drive plug 131 that has a tapered annular surface 131a remote from wall 86 to facilitate axially sliding a brush onto the plug.

Each of the brushes 118, 119 includes a tubular brush core 136 having slots 136a to permit the tubular core being moved axially onto the respective plugs 131 into driven engagement with the keys 13112 of the plugs.

Referring to FIG. 7, mounted in a fixed position in the opposite end of each tubular core is an idler plug consisting of a hub 137 having a central aperture for slidably receiving one end portion of the stub shaft 138, the opposite end of each stub shaft being rotatably mounted by a mounting member 139 in a fixed axial position relative thereto. Mounting member 139 has an outer plate portion 139a abuttable against the exterior side wall recessed portion 85a and is removably secured thereto by bolts extended through apertures in plate portion 139a and threaded into side wall portion 85a. Member 139 has an intermediate diametric portion 13% that forms a close fit with a wall defining the aperture in side wall portion 85a through which it is extended. The vertical, longitudinal crosssectional area of portion 139a is substantially larger than the corresponding area of portion 139b, while the said area of portion 139!) is substantially smaller than the corresponding area bounded by the inner wall of core 136. The inner end portion of member 137 and of shaft 138 are each of small crosssectional areas than the corresponding area of portion 13%. As a result of the above described mounting of the brushes, when a brush is to be replaced, the bolts 140 are removed and thence mounting member 139 is moved axially outwardly to a position remote from the side wall 85. This results in the shaft 138 being slidably removed from the hub 137. Now the brush core can be moved axially toward the side wall 85 a sufficient amount that the opposite axial end of the brush is adjacent the tapered surface 131a of the plug 131. Thence the brush can be readily removed from the plug 131, and the new tubular brush mounted in the housing. As may be noted from FIG. 5, the wall portion 85a having the aperture through which the plug 139 extends is spaced inwardly of the main side wall portion 850 by boss 85b.

By using the aforementioned structure for mounting the brushes, the brushes may be readily replaced without the provision of side doors but rather with apertures in the side wall of a substantially smaller diameter than the diameter of the brush. Accordingly, the side walls are of a stronger construction and may be of a unitary construction as contrasted to, for example, where doors are provided in one of the walls for removably mounting the brushes.

In order to retain liquid and debris longitudinally between the brushes in the space axially between the ends of the rotary brushes and the adjacent leg of the squeemounted in a fixed position relative the housing by a bracket 170 secured to the adjacent housing side wall (see FIG. Each of the brushes 169 is of a substantial length and is located longitudinally between peripheral portions of brushes 118, 119 that engage the surface being cleaned.

A horizontal liquid distributor 144 is mounted in the brush chamber in overhanging relationship to the forward peripheral portion of brush 118, tube 144 being fluidly connected to one end of a fluid line 148 by a fitting 145 that is extended through an aperture provided in deflector 88. Theopposite end of line 148 is fluidly connected to the bottom portion of the clean liquid solution tank 42, an operator control valve (not shown) being provided in line 148 to control the flow of fluid therethrough.

Referring to FIGS. 4 and 6, the scrubber unit squeegee assembly, generally designated 152, in horizontal plan view is generally U-shaped. Assembly 152 includes a squeegee frame member that in horizontal plan is generally U-shaped, and has a horizontal leg of approximately the same length of each side wall and underlying each side wall, and a web'portion joining the rear ends of the horizontal legs. Further, the squeegee frame 153 as viewed in vertical cross section has an upwardly extending leg 153a, a web portion 153b that has a lower edge integrally joined to the lower edge of portion 153a and a reversely bent part that is integrally joined to the upper edge of leg 153C to support it in depending relationship. Leg l53c has a terminal edge por tion 153d bent in slightly toward leg 153a. Thus, legs 153b and 153C111 combination arev somewhat U-shaped while leg 153b extends at about 90 to leg 153a in an upward direction. In order to mount the resilient squeegee 154 on frame member 153, there are provided a plurality of elongated clips 155 that are removably secured to the leg 153a by spaced nuts and bolts 156. Each clip 155 in part is somewhat L-shaped (legs 155a, 155b), and has intermediate upwardly extending leg 15519 joined to the lower edge of leg 155a, and a terminal leg l55c joined to leg 155b to be inclined relative thereto. When the clip is secured to frame member 153 such that the adjacent surface of clip leg 155a abuts or substantially abuts against leg 153a, the horizontal spacing between the terminal edge of part 153a and the horizontally adjacent part of leg 15512 is less than the horizontal thickness of the squeegee 154. At this time leg 155]) extends between web 153b and the main body part of leg 1530 and leg 1556 is inclined relative to leg 153C to extend upwardly and towards leg 153c with the juncture part of legs 155b, 1550 being abuttable against leg 153k. Accordingly, legs 1550, 153d clamp the squeegee therebetween, the squeegee being of resilient elastomeric material. Through the aforementioned structure, the squeegee 154 is mounted without any holes being made therethrough, may be one continuous strip and at the same time depends to a substantially lower elevation than the structure mounting the squeegee. Further the squeegee may be easily removed and turned so that each of the four comer edge portions 154a may be used.

In order to mount the squeegee assembly 152 on the housing there is provided a pair of leaf springs 159 that have their one ends mounted on the bottom edge of the adjacent side wall and their opposite ends attached to the frame member 153 (see FIG. 4). The transverse width of the springs 159 is many times greater than the thickness thereof while the longitudinal lengths of the springs is many times greater than the transverse width thereof. Thus, the squeegee assembly 152 is mounted for limited vertical movement relative the housing and is resiliently urged to a position the squeegee 154 abuts against the surface to be cleaned when the brushes bear against the surface to be cleaned. At such a time, the frame member 153 is substantially vertically spaced from the lower edges of the side walls and the springs, due to their width, retain the frame member 153 in proper transverse relationship to the scruber unit hous- At times it is desired to go over the surface to be cleaned without collecting the liquid from the surface. Accordingly, it is desirable to be able to lift the squeegee assembly 152 from the surface. In order to achieve this, there is provided a pair of rods 161, each rod having its lower end attached to the longitudinal leg of the squeegee assembly 152 a short distance forwardly of the web of such assembly (see FIGS. 7 and 8). The opposite end of each rod 161 is pivotally connected to the outer end of an arm 162. The other end of each arm 162 is pivotally mounted on the housing by pivot member 163 to pivot about a longitudinal axis. A lever 164 is connected to each arm 162 to pivot it about pivot 163. Each lever extends through appropriately shaped notched slots in channel 96, the slots being of appropriate shapes and there being provided resilient means (not shown) to releasably retain the lever in a position that the squeegee frame member 153 is held closely adjacent the bottom edges of the side walls to substantially space the squeegee from the surface being cleaned. Upon moving the levers to elevate the squeegee assembly the web portion is elevated so that the adjacent corner abut against the side wall and thence the side leg of the squeegee generally pivots to further raise the front end portion thereof. Upon moving the levers 164 to a squeegee assembly lowering position, the springs 159 move the squeegee assembly downwardly to bear against the surface being cleaned, provided the housing is at an elevation below the transport position.

In order to withdraw liquid collected by the squeegee assembly 152 on the surface being cleaned, there is provided a liquid take-up member 167 mounted by the web portion of the squeegee assembly to move therewith (see FIG. 4). The take-up member 167 is slidably extended through an aperture in channel bottom wall 101a and has its upper end fluidly connected to conduit 34. It is to be noted that the hopper rear wall and bot tom wall each has a transversely intermediate portion that in plan view is somewhat arcuately curved to provide a recess for the tube 34 to extend downwardly between the rear wall and the channel portion 10lb to permit liquid pick-up member 167 and tube 34 being moved vertically relative the hopper.

Referring to FIG. 2, it is to be noted that the maximum transverse width X of the scrubbing unit in a horizontal condition is substantially greater than the maximum transverse width W of the power unit. For example, one model of machine has a transverse width X of about 37 inches while the transverse width W is about 30 inches. In order to facilitate the surface cleaning machine 10 being moved through a doorway of the width of, for example, 31 inches, the scrubber unit may be rotated about the central longitudinal axis of shaft 65 from the predominantly horizontal position 120 to the predominantly vertical position 12d as the height H of the scrubber unit in the horizontal condition is substantially less than the dimension W, the shaft 65 is connected to the upper rear portion of the housing substantially more closely adjacent the top than the lower part of the housing and the shaft 65 is located substantially closer to the side wall 86 than the side wall 85. The housing in the horizontal elevated rotatable position (dotted line position 12c of FIG. 2) may be pivotally rotated in the direction of arrow 172 as shown in FIG. 2 about the shaft 65 in its elevated position 65a. Due to the location of the motor and the construction of the housing, the center of gravity of the housing in its vertical position 12a of FIG. 2 is located to the left of shaft 65 in position 650. Accordingly, when in its vertical condition, the housing tends to rotate in a direction opposite arrow 172. In order to prevent such rotation, a lock rod 173 has one end pivotally connected to the support member 66 by a spherical bearing 175 at a location vertically above the shaft 65 when the support member 66 is in a vertically extending condition (see FIG. A spring clip (not shown) is provided for selectively retaining the lock rod in an out of the way position. The opposite end of the lock rod is extendable into an upwardly opening recess provided in the lug 174 that is welded to the top surface of the support member 54, the lug being located to the left of the shaft 65 as viewed in FIGS. 2 and 10. Accordingly, with the lock rod extending into the lug recess, the housing is prevented from rotating in a direction opposite arrow 172. However; when its desired to return the scrubber unit to a generally horizontal condition, first the scrubber unit is rotated a few degrees further in the direction of the arrow 172 from that illustrated in FIG. 10 to move the end of the lock rod out of the lug recess and thence the lock rod is pivoted about spherical bearing 175 to have its opposite end located longitudinally between channels 54, 66. At this time, the housing will swing back to be generally horizontal condition.

To be noted is that when the scrubber unit is in a generally horizontal condition, the center of gravity is located at a lower elevation than the shaft 65 and slightly more closely adjacent side wall 86 than the vertical plane of the central axis of shaft 65.

Referring to FIGS. 2 and 8, in order to limit the pivotal movement of the scrubber head unit about shaft 65 in a direction opposite arrow 172 to a position that support member 66 extends generally horizontally, a lug 178 is welded to support member 54 to extend in underlying relationship to support member 66 at a location to the left of shaft 65 as viewed in FIG. 2. The lug has an adjustment bolt 179 slidably extended therethrough, a nut being threaded on the bolt for adjustably limiting the upward movement of the bolt relative the lug. A coil spring 179a has one end bearing against the head end of the bolt and an opposite end against the lug for constantly resiliently urging the bolt upwardly whereby the bolt in its uppermost position abuts against the underside of support member 66 to resiliently limit the rotation of support member 66 in the direction opposite arrows 172 to a horizontal position. Thus members 178, 179, 179a limit the pivotal movement of the scrubber head in the direction opposite arrow 172, resiliently oppose movement in said direction past a horizontal position, and permits limited movement past a horizontal position to permit the brushes remaining in engagement with uneven surfaces being cleaned.

To releasably retain the support member 66 in a generally horizontal condition but to permit its pivoting a limited amount in the direction of the arrow 172 from a substantially horizontal condition so that the brushes along the axial length thereof may pivot about a longitudinal axis to remain in engagement with uneven surfaces being cleaned, there is provided a lock assembly generally designated 183. The lock assembly includes a vertical rod 184 that is mounted for rotation about a vertical axis by the frame member 66, the rod extending upwardly through an appropriate aperture in the panel 96 and having a lever 185 keyed to the upper end thereof for rotating the rod about its central axis. An annular member 186 is fixedly secured to rod 184 vertically between the horizontal surface of the panel 96 and the top surface of support member 66, a coil spring 187 being provided on the rod to have an upper end abut against annular member 186 and a lower end abut against support member 66 for resiliently urging the rod in an upward direction. To the lower end of the rod 184 there is joined a generally horizontal arm 188 that is of a length to have the outer end thereof extendable beneath support member 54. To be noted, is that the rod 184 and the arm 188 when extending beneath the support member 54, are transversely more remote from the vertical plane of the central axis of the shaft 65 than the adjustment bolt 179. Accordingly, when the lock assembly 183 is in a locking position that arm 188 extends beneath the support member 54, the scrubber head unit support member 66 is free to pivot in the direction of the arrow 172 a limited amount from the horizontal condition abutting against the top bolt 179 to a position the spring 187 is fully compressed. It is to be understood that when arm 188 is out of a position extending beneath support member 54, the spring 187 lifts the rod 184 to a position that arm 188 is above the bottom surface of support member 54. Thus, when it is desired to return the lock assembly 183 to the position illustrated in FIG. 8, either a cam (not shown) is provided to move the rod downwardly as it is turned, or else it is necessary that the lever 185 be pushed downwardly and thence turned.

It is to be noted that if the lock lever is rotated from the position illustrated in FIG. 8 and is moved vertically upwardly from said position through the action of spring 187, the arm 188 will be in overlying relationship to the top wall 103 when the hopper is in the liquid collecting position of FIG. 4. Accordingly, at that time the lock member 183 will serve to hold the baffletrough unit in the liquid collecting position illustrated in FIG. 4, and the scrubber head unit may be rotated to its vertical condition without danger of the bafflehopper falling out of the housing.

The baffle 109 of the combination baffle holler has a flange 109a secured to the top wall 103, a main body portion 10% that extends parallel to the panel 89 and an upper flange 109a that extends generally horizontally and parallel to channel web 101a when the hopper is in the position of FIG. 4. Flange 1090 in the FIG. 4 position facilitates the withdrawal of the baffle-hopper from the housing. Further, the main body portion 10% is located substantially more closely adjacent panel 89 than panel flange 96a.

When it is desired that the liquid raised by the brushes be recirculated to the floor, the baffle-hopper is withdrawn from the housing, rotated 180 about a longitudinal axis, and thence reinserted through an opening 97 to have the juncture of baffle portions 1090, 109b bear against the channel web 101a. Baffle portion is retained generally parallel to panel portion 89a, due to the hopper walls front edges abutting against panel portion 89b and the upper rear edge portions thereof being closely adjacent panel portion 960 as shown in FIG. 8. At this time, liquid raised by the brushes and passing through the upper part of the opening 102 will roll down along the top wall 103, which is now inclined downwardly and forwardly, to fall onto the rear brush 118, while the liquid moving rearwardly through the lower part of the opening 102 will strike baffle portion 10%, part of which will fall back onto the brush 118 and part of which will move down into the channel 101. The channel has one or.

more openings in web 101a to permit the liquid to drain back onto the surface being cleaned.

Referring to FIGS. 12 and 13, the front wheel assembly, generally designated 14, of the power unit includes the front wheel 195 that is mounted on a hub 196 to rotate therewith. The hub is keyed to the motor shaft 197 of the hydraulic motor 198. The motor is mounted by the front wheel support ,199, the support 199 being mounted on the main frame portion 11a for steerable movement in the manner similar to that described in US. Pat. No. 3,604,051 other than said patent discloses the mounting of a rear steerable wheel.

Hub portion 1961) forms a brake drum having an inner cylindrical surface portion against which the internally expansible arcuate brake shoes 200, 201 having thereon brake linings that may bear for braking engagement with the drum. The lower end portion of the shoes are pivotally mounted by a pivot member 203 that in turn is secured to the support, coil springs 204 and 205 being attached to the shoes for resiliently retaining them in their non-braking retracted position. A cam 206 is keyed to a rocker arm shaft 207 to extend downwardly between the upper terminal ends of the shoes 200, 201 and is movable between a datum position that the shoe linings are in a braking condition with reference to the brake drum and a release position. The shaft 207 is pivotally mounted by a support 199, the end of the shaft remote from cam 206 having a mid portion of the rocker arm 208 keyed thereto. A spring plunger member 109 as one end mounted by the support and an opposite end pivotally connected at 210 to one end of arm 108 for constantly resiliently urging the arm to pivot to a position that the cam forces the brakeshoes and brakeshoe linings into braking engagement with the brake drum. The spring characteristics of the spring of member 209 are sufficient to move the brake shoes to a braking position against the action of springs 204 and 205. The opposite end of the rocker arm is pivotally connected at 212 to the piston rod 21 1 of the piston cylinder combination to 211, 212. The aforementioned combination includes a cylinder 212 that is pivotally connected to the support 199 by pivot member 214. When fluid under pressure is applied to the cylinder 212 the piston rod is moved to an extended condition to move the rocker arm to release the braking condition. As a result of the provision of the aforementioned structure, the front wheel is continuously braked unless fluid under pressure is applied to the cylinder 212.

In place of the brake drum surface, the hub may be provided with a brake disc; and in place of the disclosed brake shoes, there may be provided suitable brake shoes for bearing against the brake disc, the last mentioned shoes being operated between braking and non-braking positions through a suitable linkage that in turn is operated by thepreviously described movement of the rocker arm.

Referring to FIG. 11, the hydraulic circuitry and drive components, generally designated 220, will be briefly described since they are similar to that described in copending application Ser. No. 85,468, filed Oct. 30, I970. The hydraulic circuitry and components 220 includes an electric motor 221 drivably connected to fixed displacement pump 222 and a variable displacement swash plate, overcenter piston type pump 223. Pump 223 is fluidly connected by pressure and return lines 224 for driving the motor of 198 in the desired direction, depending upon the setting of control 225 of the pump 223. Control 225 is connected by a suitable linkage to lever 250 (see FIG. 1) at the back of the power unit. Further, supply line 226 fluidly connects the pump 223 to reservoir 228 while there is provided a return line 227 between the reservoir and said pump.

An additional pressure line 230 is fluidly connected to the pump 223 and to the pressure port of a two position, solenoid operated valve 231 that is controlled by a control (not shown) adjacent the steering wheel. A second port of said valve is fluidly connected by line 232 to one end of the brake cylinder 212. A third port of the valve is connected by a line 233 to a line 234 which is connected to the reservoir. When the valve 231 is in one of its two positions, the pressure line 230 is fluidly connected to line 232 for applying fluid under pressure to the brake cylinder 212, while in the second position, the pressure port is blocked and line 232 is fluidly connected through the valve to the reservoir through lines 233, 234 to permit the exhausting of fluid from the cylinder.

A line 236 connects the reservoir to the inlet port of the pump 222 which is driven by motor 221 while line 237 connects said pump to the inlet port of a four-way valve 239. The second port of the valve is connected by a return line 238 to the reservoir while the third port is connected by line 240 to one port of the brush motor 121, the second port of the brush motor being connected by line 241 to line 238. The fourth port of the valve 239 is connected by line 242 to one end of the cylinder 58 while the opposite end of the cylinder has line 234 connected thereto.

By operating the valve through a lever (not shown) on the control panel to its first position, fluid under pressure is applied to neither brush motor 121 nor cylinder 158; a second position, fluid under pressure is applied to line 240 and line 242 is fluidly connected to line 238; and a third position, line 240 is fluidly connected to return line 238 and line 237 is fluidly con nected to line 242 for operating the cylinder 58 to elevate the scrubber head unit. In the valve second position, fluid exhausts from the cylinder 58 through lines 242, 238, whereby the weight of the scrubber unit acts to retract the piston rod 59. An adjustable pilot operated valve 238a and a filter are provided in line 238.

Referring to FIG. 9, it is to be noted that the housing of electric motor 221 is bolted to a plate 350 which in turn is hingedly connected at 246 to a housing 247. The

hinge axis of hinge 246 is vertical. Housing 247 also mounts the housing of one of the pumps, for example pump 223, the other pump 222 being mounted on motor 221. The shaft 221a of motor 221 rotatably extends through plate 350 and has a coupling member 22lb keyed thereto that may be pivoted into an axially alinged, driving relationship with a coupling member 223a that is keyed to the pump shaft 223!) of the pump 223 to be located within the housing 247. A few bolts 350a, for example, three are extended through housing 247 and threaded into plate 350 to hold the motor 221 in the solid line position of FIG. 9. When the pump and electric motor shafts are axially aligned, the shafts extend transversely, the housing 247 being mounted on a frame member 249 to extend thereabove. Frame member 249 and the housing 247 mount the electric motor at the lower rear portion of the main frame, the power unit not having any structure other than the bolts extended through plate 350 and threaded into housing 247 to prevent the motor 221 being moved to the dotted line position of FIG. 9 whereby the brush end of the motor extends rearwardly of the main frame. As a result, by removing bolts 350a, the electric motor may be pivoted about the hinge axis of hinge 246 to have the end remote from coupling 22lb extend slightly rearwardly of the main frame. In this connection, it is to be mentioned that the brushes of the motor are located on the end portion remote from hinge 246, and thus the aformentioned mounting of the electric motor readily permits carrying out certain maintenance operations on the motor without the requirement of removing any panels or the removal of the motor from the main frame.

Referring to FIGS. 16 and 15, there is partially illustrated a second embodiment of this invention that includes a power unit, generally designated 275, and a scrubber head unit, generally designated 276. The unit 275, 276 are the same as units 11 and 12 respectively other than for the differences noted hereinafter. In place of a single support 54 of the first embodiment, the second embodiment includes a pair of verticallyspaced, parallel support bars 278 that have their opposite ends mounted by the vertical bars 50. To the transverse mid portion of each of the bars 278, the one ends of the arms 279 are pivotally attached by pivot members 280. The opposite ends of the arms 279 are pivot ally connected at 281 to lugs 282. The lugs are welded to vertical plate 283, plate 283 in turn having one end of the shaft 65 welded thereto. The shaft in turn pivotally mounts support member 66 of the scrubber unit 276 in the same location relative thereto as described with reference to support member 66 of the first embodiment of the invention pivotally mounting the scrubber head unit 12. Through the aforementioned structure of the second embodiment, scrubber head unit 276 may be pivoted about the axes of pivots 280 from the solid line position of FIG. 15 to the dotted line position thereof while the scrubber head unit may be pivoted about pivots 281 to maintain the scrubber head unit such that the transverse axes of rotation of the brushes can be maintained parallel to the original position of said brushes. As a result, the scrubber head unit may be moved to a position laterally offset from the normal solid line position of FIG. 15. In the solid line position, the shaft 66 is located relative the power unit such as described with reference to the first embodiment. The second embodiment includes a second lug (not shown) on the upper bar 278 for receiving the lock rod 173 when the scrubber head unit in the dotted line position of FIG. 15 is rotated about shaft 65 to a vertical condition. A suitable lock pin (not shown) may be provided for locking arms 179 in either the dotted line or a solid line position of FIG. 15. With the arms 179 locked in the dotted line position and the lock rod retaining the scrubber head in a vertical condition after having been first horizontally offset to the dotted line position of FIG. 15, the brushes will extend further transversely outwardly beyond the right side of the power unit as viewed in FIG. 15. As a result, it is possible to use the scrubber head unit for cleaning vertical surfaces such as vertical walls as the power unit moves adjacent and parallel thereto in a normal longitudinally forward direction; it being understood, that if liquid is sprayed onto the brushes that the liquid would be squeegeed off the wall surface and drained onto the floor to be subsequently picked up when the scrubber head unit is operated in a horizontal condition.

The lever 250 for operating the control 225 of the variable displacement pump 223 is mounted on the back of the main frame and is located at a height that a persons arm holding it will have his lower arm in a general horizontal condition. Further, the vertical handle of the lever extends rearwardly of the machine sufficiently that if the seat, including bar 21, has been removed and the operator is walking in back of the machine and backs into the wall, the upper part of the arm will bump into the wall and force the lever forwardly. When the lever is moved forwardly, the pump 223 is driven in a direction to move the machine forwardly, this being a safety feature to help prevent accidental squeezing a person against the wall.

Not previously mentioned is that the wheel support is pivotally mounted on the main frame at frame portion 11a at a location to the rear of support member 54 and transversely intermediate parallel arms 52. Additionally, the main frame has a battery compartment floor 254 of generally U-shaped configuration with the parallel arms 52 being located transversly between the legs of the floor and the web of the floor being located rearwardly of the arms. The floor is relatively low, for example not more than about 6 or 7 inches above the surface being cleaned. One of the legs of the compartment floor is located transversely between the side panel llr of the power unit and the vertical compartment wall that is adjacent one of the upper and lower pair of arms 48, 52 while the other leg is between the power unit side panel llt and the vertical wall 115 adjacent the other upper and lower pair of arms 48, 52. As a result, the batteries 253 for supplying power to the electric motor are located around three sides of the propelling front wheel so that optimum weight factors are supplied to the wheel for good traction. Additionally the side panels llr and llt are hingedly mounted on the frame or are easily removable to facilitate easy removability of the bateries.

Also, the batteries are located around the propelling wheel at the lowest possible level to provide a very low center of gravity for the power drive unit. Additionally, the compartment in which the batteries are located is directly beneath the cleaning solution tank, and thus, upon pivoting the cleaning solution tank to the dotted line position of FIG. 1, ready access is had to the batteries. Further, with the cleaning solution tank located above the batteries, it provides a greater head pressure to send the solution to the spreader tube 144 and thereby to eliminate the necessity of a pump.

The chamber 93 in addition to having the brush motor 121 located therein, provides space in which any one of a number different devices may be located. For example, in such space there may be provided any one of a on-board battery charger, a built in foam generator, a built in powered wax sprayer, or a rubber mark removal sprayer.

With the apparatus of this invention and the arms 48 of the parallel linkage assembly located below the level of lock plate edge 71b, the scrubber head is mounted for limited free floating movement in a vertical direction (if both ends of the lift cylinder are fluidly connected to the reservoir) and can pivot a limited amount about shaft 65 within the limits allowed by stop bolt 179 and the spring action of spring 179a and the spring action of spring 187. With the combination bafflehopper in the liquid collecting position of FIG. 4, liquid and debris raised by the brushes in passing through the opening 102 is collected in the trough and liquid is withdrawn therefrom through the conduit 35 to be collected in the dirty solution tank. The liquid not collected by the trough is collected by the scrubber head squeegee and returned to the collection tank 30 through the conduit 34, the remaining liquid on the surface being collected by the rear squeegee assembly 37.

In the event it is desired to usethe apparatus of this invention for sweeping, no vacuum would be applied to the dirty solution tank 30 and material raised by the brushes would be collected in the trough in the FIG. 4 position. a

It it is desirable to go over the surface to scrub and soak it without collecting liquid the first time, the squeegee assemblies 37 and 152 can be raised and locked in the raised positions such that liquid remains on the surface as the machine moves thereover. At this time, the baffle trough combination would be positioned such as illustrated in FIG. 8 whereby the liquid raised by the brushes would run back down onto the surface.

-When it is desired to move from one location to the other, piston-cylinder combination 58, 59 may be operated to raise the parallel linkage assembly to the location that the arm 48 which is adjacent plate 71 is moved into the plate notch in part defined by edges 71b, 71d and thence lowered onto an edge 71b. At this time, even though the squeegee assembly 152 is not locked in the raised position, both the squeegee assembly 152 and the brushes would be at an elevation substantially above the surface to be cleaned.

If the apparatus of this invention is to be passed through a narrow doorway that is of a width smaller than the scrubber head unit in a horizontal position but greater than the width of the power drive unit, and if the rear squeegee assembly is of a greater width than the power unit, the rear squeegee assembly may be removed, the scrubber head unit raised to its elevated turning position, lock assembly 183 operated to move arm 188 from beneath channel 54, and then the scrub her head unit rotated 90, and the lock rod 173 moved to. its locking position of FIG. 9 to block rotation of the scrubber unit in the direction opposite arrow 172.

By modifying the shape of plate 71 including providing another notch therein, the scrubber head unit may be selectively retained in a horizontal condition at an intermediate elevation between the free float position and the transport position. At the intermediate elevation the brushes would be vertically spaced from the surface being cleaned, however, the rear squeegee assembly in its datum position relative the scrubber head housing would engage the surface to collect and pick up liquid.

What is claimed is:

1. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame, and a surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool enclosure, a rotatable surface engaging maintenance tool and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a support member, second means mounted on the support member to move therewith and mounting the surface maintenance unit for movement with the support member and pivotal movement relative the support member, and power operated parallel linkage means mounted on the main frame for mounting the support member-and selectively moving the support member, and therethrough, the surface maintenance unit between an elevation in which the tool engages said surface and an elevation in which said tool is substantially spaced from said surface.

2. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame and a power driven surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool, and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a support member, a pivot member having a predominantly horizontally extending pivot axis for mounting said surface maintenance unit for pivotal movement between a generally horizontally extending position in which the tool is engageable with the surface to be cleaned and a vertically extending position at about 90 relative thereto, said pivot member being mounted on the support member to move therewith and power operated lift means for moving the support member and therethrough the surface maintenance unit between an elevation in which the tool engages said surface when the surface maintenance unit is in a horizontal position, and an elevation permitting the surface maintenance unit to be rotated between said horizontal position and said vertical position, said units having cooperating means for releasably locking the surface maintenance unit in its generally vertical position.

3. The apparatus of claim 2 further characterized in that the surfacemaintenance unit in a horizontal position has a substantially greater transverse width than the maximum transverse width of power unit, and a height substantially less than its transverse width.

4. The apparatus of claim 3 further characterized in that said surface maintenance unit has opposite transverse sides and is mounted on said pivot member to have one transverse side thereof substantially more closely adjacent said pivot member than the other side when said surface maintenance unit is in a horizontal position.

5. The apparatus of claim 3 further characterized in that the surface maintenance unit in a vertical position has a center of gravity offset from the pivot axis and thereby under the action of gravity tends to rotate about the pivot axis in one angular direction, that there is provided stop means on the support member for limiting the rotative movement of the surface maintenance unit about said axis in said one angular direction from the vertical position toward the horizontal position to a generally horizontal position, and that said surface maintenance unit includes a housing and control means on the housing for selectively abutting against the sup port member to retain the surface maintenance unit in a predominantly horizontal position while permitting limited angular movement about said axis and resiliently urging said surface maintenance unit toward a position to abut against said stop means.

6. The apparatus of claim 5 further characterized in that said lift means includes upper and lower parallel arms each having one end pivotally connected to the main frame to pivot about horizontal axes and opposite ends, and bar means pivotally connected to said opposite ends for mounting the support member for vertical movement as the arms are pivoted about said horizontal axes.

7. The apparatus of claim 6 further characterized in that said surface maintenance unit includes a transverse frame member mounting said housing, said housing having opposite side walls and said enclosure that is in part defined by said side walls, first means for pivotally mounting said frame member on the pivot member to pivot about the pivot member axis, said first means being joined to said frame member at a location substantially more closely adjacent one of said side walls than the other, that the control means includes a vertical rod pivotally mounted by the frame member to extend above and beneath the frame member when the maintenance unit is in a horizontal position, resilient means connected to said rod for constantly resiliently urging the rod upwardly, an arm joined to the lower end of said rod to rotate therewith to a position extendable beneath said support member, and a handle connected to the upper end of said rod for moving the rod downwardly, and pivoting the rod to move the last mentioned arm beneath the support member, and alternately pivoting the rod to move the last mentioned arm away from the support member to permit the surface maintenance unit pivoting 90 relative the pivot member.

8. The apparatus of claim 7 further characterized in that said tool comprises a scrubbing tool, that said housing has a top hopper insert opening, that the maintenance unit includes a hopper having a debris inlet opening and a trough portion beneath said inlet opening, and means for mounting the hopper in the housing in a position for material raised by said tool to be able to pass through said inlet opening, and for free withdrawal through said top opening, said housing having an opening between the enclosure and the hopper unit to permit raised material to pass into the hopper, and that the rod and arm thereon are pivotable to a position to hold the hopper in the housing even when the housing is turned about 90 about the first mentioned axis.

9. The apparatus of claim 5 further characterized in the said lift means includes an arm having one end portion and an opposite end, second means for mounting the support member on the arm opposite end to move therewith, third means for mounting said arm one end portion on the main frame for pivotal movement about a horizontal axis and selectively pivoting said arm about the last mentioned axis for moving the opposite end and therethrough the maintenance unit to various elevations, and that said power unit has operable lock means for releasably retaining said arm in a first pivotal position that the maintenance unit is vertically spaced from the surface to be cleaned.

10. The apparatus of claim 9 further characterized in that the lock means comprises a latch plate movably mounted on the main frame and having a first portion for retaining said arm in the arm first pivotal position, and a second portion for retaining said arm in a second pivotal position in which the maintenance unit is at a substantially higher elevation than in the arm first pivotal position and at an elevation that the maintenance unit may be freely turned through said angle, said arm first pivotal position positioning the surface maintenance unit at an elevation that upon attempting to turn the surface maintanance unit through said 90 angle, the maintenance unit would abut against said surface to limit the pivotal movement to an angle substantially less than 90, and means connected to said latch plate for selectively moving said latch plate out of the path of movement of said arm and returning said latch plate into the path of movement of said arm.

11. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame and a power driven surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool enclosure, a rotatable surface engaging maintenance tool, and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a power operated lift assembly for mounting the maintenance unit on the main frame and selectively moving the maintenance unit between a lowered first position in which said tool engages said surface and an elevated second position in which said tool is substantially spaced from said surface, said lift assembly including a support member, first means for mounting the maintenance unit on the support member for movement therewith, a linkage device attached to the support member for moving the support member therewith and mounted on the main frame for movement between the maintenance unit first and second positions, power means for moving said linkage device between the above positions, and latch means mounted on the frame for movement between a first position abutting against the linkage device for retaining the linkage device in the maintenance unit tool elevated position and a second position out of the path of movement of the linkage device as the linkage device moves between the maintenance unit positions, and second means for selectively moving the latch means between its positions.

12. The apparatus of claim 1 further characterized in that said parallel linkage means includes a first pair of vertically spaced parallel arms each having one end pivotally connected to the frame, and each having an 21 opposite end, a first bar pivotally mounted by the first arms opposite ends, a second pair of vertically spaced parallel arms offset from the first pair of parallel arms in a direction transverse to the normal direction of movement of the machine and parallel to said first pair of arms, said second pair of arms each having one end pivotally connected to the frame and opposite ends, and a second bar pivotally mounted by the second arms opposite ends, said support member being fixedly attached to said bars to move therewith.

13. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame, and a surface engaging wheel assembly mounted on they main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool enclosure, a rotatable surface engaging maintenance tool and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a lift assembly for mounting the maintenance unit on the main frame and selectively moving the maintenance unit between a lowered first position in which said tool engages said surface and an elevated second position in which said tool is substantially spaced from said surface, said lift assembly including a parallel linkage assembly mounted on the main frame and having a support member movable between a position in which said tool engages said surface and a tool elevated position, operator controlled means for moving said parallel linkage assembly, andsecond means mounted on the support member to move therewith for mounting the surface maintenance unit for movement with the support member and pivotal movement relative thereto, the second means including a generally horizontal pivot member having a generally horizontal pivot axis and third means for mounting said pivot member on the support member for movement between a datum first position and a second position, the surface maintenance unit including means for mountin g the housing on said pivot member for pivotal movement about said horizontal axis, said housing being mounted on said pivot member for angular movement through an angle of about 90 between a datum position in which the tool extends downwardly of the housing and a second position in which the tool extends laterally outwardly of the housing, and said third means being of a horizontal length to, in the pivot member second position, position the housing in the housing second position so that the said tool is engageable with a vertical surface as the power unit moves forwardly parallel to said vertical surface and adjacent thereto.

14. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame, and a surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool enclosure, a rotatable surface engaging maintenance tool and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a lift assembly for mounting the maintenance unit on the main frame and selectively moving the maintenance unit between a lowered first position in which said tool engages said surface and an elevated second position in which said tool is substantially spaced from said surface, said lift assembly including a parallel linkage assembly mounted on the main frame and having a support member movable between a position in which tool engages said surface and a tool elevated position, operator controlled means for moving said parallel'linkage assembly, second means mounted on the support member to move therewith for mounting the surface maintenance unit for movement with the support member and pivotal movement relative thereto, said second means comprising a pivot member having a pivot axis extending generally longitudinally in the direction of normal movement of the machine, said pivot member being mounted on the support member, and means for mounting the surface maintenance unit on the pivot member for pivotal movement about said axis through a substantial angle from a predominantly horizontal position to a predominantly vertical position and cooperating means on the power unit and the surface maintenance unit for releasably retaining the surface maintenance unit in said vertical position.

15. The apparatus of claim 14 further characterized in that the surface maintenance unit in a horizontal position has a substantially greater transverse width than the minimum transverse width of the main frame and a height substantially less than its transverse width.

16. The apparatus of claim 15 furthercharacterized in that the housing has transversely spaced first and second side walls that in part define said enclosure, that the pivot member is located substantially transversely more closely adjacent the first side wall than the second side wall when the surface maintenance unit is in a horizontal position, and that the surface maintenance unit includes third means mounted on the housing for cooperating with the parallel linkage assembly for releasably retaining the housing in a predominantly horizontal position. I

17. The apparatus of claim 16 further characterized in that the surface maintenance unit in a horizontal position has a center of gravity that in a transverse direction is located between said pivot axis and the second side wall and more closely adjacent the pivot axis than the second wall.

18. The apparatus of claim 17 further characterized in that the housing includes a frame member, that the third means includes a control member mounted on the frame member for pivotal movement about a second pivot axis between a first position engaging the support member to retain the surface maintenance unit in a predominantly horizontal position and a second position permitting the surface maintenance unit being rotated about the first pivot axis through an angle of about and slidably movement relative the frame member along said second pivot axis and resilient means acting against the control member to resiliently urge the control member to a slidable position that the control member in its first pivotal position abuts against the support member.

19. The apparatus of claim 18 further characterized in that said surface maintenance unit includes a debris hopper, that said housing has a top hopper insert opening and means for slidably receiving said hopper when inserted through said top opening and supporting said hopper in a position to receive material raised by said tool, said enclosure having an opening for material raised by said tool moving into said hopper, and that said control member has an arm for abutting against the hopper to block the hopper from moving out of the 

1. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame, and a surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool enclosure, a rotatable surface engaging maintenance tool and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a support member, second means mounted on the support member to move therewith and mounting the surface maintenance unit for movement with the support member and pivotal movement relative the support member, and power operated parallel linkage means mounted on the main frame for mounting the support member and selectively moving the support member, and therethrough, the surface maintenance unit between an elevation in which the tool engages said surface and an elevation in which said tool is substantially spaced from said surface.
 2. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame and a power driven surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool, and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a support member, a pivot member having a Predominantly horizontally extending pivot axis for mounting said surface maintenance unit for pivotal movement between a generally horizontally extending position in which the tool is engageable with the surface to be cleaned and a vertically extending position at about 90* relative thereto, said pivot member being mounted on the support member to move therewith and power operated lift means for moving the support member and therethrough the surface maintenance unit between an elevation in which the tool engages said surface when the surface maintenance unit is in a horizontal position, and an elevation permitting the surface maintenance unit to be rotated between said horizontal position and said vertical position, said units having cooperating means for releasably locking the surface maintenance unit in its generally vertical position.
 3. The apparatus of claim 2 further characterized in that the surface maintenance unit in a horizontal position has a substantially greater transverse width than the maximum transverse width of power unit, and a height substantially less than its transverse width.
 4. The apparatus of claim 3 further characterized in that said surface maintenance unit has opposite transverse sides and is mounted on said pivot member to have one transverse side thereof substantially more closely adjacent said pivot member than the other side when said surface maintenance unit is in a horizontal position.
 5. The apparatus of claim 3 further characterized in that the surface maintenance unit in a vertical position has a center of gravity offset from the pivot axis and thereby under the action of gravity tends to rotate about the pivot axis in one angular direction, that there is provided stop means on the support member for limiting the rotative movement of the surface maintenance unit about said axis in said one angular direction from the vertical position toward the horizontal position to a generally horizontal position, and that said surface maintenance unit includes a housing and control means on the housing for selectively abutting against the support member to retain the surface maintenance unit in a predominantly horizontal position while permitting limited angular movement about said axis and resiliently urging said surface maintenance unit toward a position to abut against said stop means.
 6. The apparatus of claim 5 further characterized in that said lift means includes upper and lower parallel arms each having one end pivotally connected to the main frame to pivot about horizontal axes and opposite ends, and bar means pivotally connected to said opposite ends for mounting the support member for vertical movement as the arms are pivoted about said horizontal axes.
 7. The apparatus of claim 6 further characterized in that said surface maintenance unit includes a transverse frame member mounting said housing, said housing having opposite side walls and said enclosure that is in part defined by said side walls, first means for pivotally mounting said frame member on the pivot member to pivot about the pivot member axis, said first means being joined to said frame member at a location substantially more closely adjacent one of said side walls than the other, that the control means includes a vertical rod pivotally mounted by the frame member to extend above and beneath the frame member when the maintenance unit is in a horizontal position, resilient means connected to said rod for constantly resiliently urging the rod upwardly, an arm joined to the lower end of said rod to rotate therewith to a position extendable beneath said support member, and a handle connected to the upper end of said rod for moving the rod downwardly, and pivoting the rod to move the last mentioned arm beneath the support member, and alternately pivoting the rod to move the last mentioned arm away from the support member to permit the surface maintenance unit pivoting 90* relative the pivot member.
 8. The apparatus of claim 7 further chAracterized in that said tool comprises a scrubbing tool, that said housing has a top hopper insert opening, that the maintenance unit includes a hopper having a debris inlet opening and a trough portion beneath said inlet opening, and means for mounting the hopper in the housing in a position for material raised by said tool to be able to pass through said inlet opening, and for free withdrawal through said top opening, said housing having an opening between the enclosure and the hopper unit to permit raised material to pass into the hopper, and that the rod and arm thereon are pivotable to a position to hold the hopper in the housing even when the housing is turned about 90* about the first mentioned axis.
 9. The apparatus of claim 5 further characterized in the said lift means includes an arm having one end portion and an opposite end, second means for mounting the support member on the arm opposite end to move therewith, third means for mounting said arm one end portion on the main frame for pivotal movement about a horizontal axis and selectively pivoting said arm about the last mentioned axis for moving the opposite end and therethrough the maintenance unit to various elevations, and that said power unit has operable lock means for releasably retaining said arm in a first pivotal position that the maintenance unit is vertically spaced from the surface to be cleaned.
 10. The apparatus of claim 9 further characterized in that the lock means comprises a latch plate movably mounted on the main frame and having a first portion for retaining said arm in the arm first pivotal position, and a second portion for retaining said arm in a second pivotal position in which the maintenance unit is at a substantially higher elevation than in the arm first pivotal position and at an elevation that the maintenance unit may be freely turned through said 90* angle, said arm first pivotal position positioning the surface maintenance unit at an elevation that upon attempting to turn the surface maintanance unit through said 90* angle, the maintenance unit would abut against said surface to limit the pivotal movement to an angle substantially less than 90*, and means connected to said latch plate for selectively moving said latch plate out of the path of movement of said arm and returning said latch plate into the path of movement of said arm.
 11. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame and a power driven surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool enclosure, a rotatable surface engaging maintenance tool, and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a power operated lift assembly for mounting the maintenance unit on the main frame and selectively moving the maintenance unit between a lowered first position in which said tool engages said surface and an elevated second position in which said tool is substantially spaced from said surface, said lift assembly including a support member, first means for mounting the maintenance unit on the support member for movement therewith, a linkage device attached to the support member for moving the support member therewith and mounted on the main frame for movement between the maintenance unit first and second positions, power means for moving said linkage device between the above positions, and latch means mounted on the frame for movement between a first position abutting against the linkage device for retaining the linkage device in the maintenance unit tool elevated position and a second position out of the path of movement of the linkage device as the linkage device moves between the maintenance unit positions, and second means for selectively moving the latch means between Its positions.
 12. The apparatus of claim 1 further characterized in that said parallel linkage means includes a first pair of vertically spaced parallel arms each having one end pivotally connected to the frame, and each having an opposite end, a first bar pivotally mounted by the first arms opposite ends, a second pair of vertically spaced parallel arms offset from the first pair of parallel arms in a direction transverse to the normal direction of movement of the machine and parallel to said first pair of arms, said second pair of arms each having one end pivotally connected to the frame and opposite ends, and a second bar pivotally mounted by the second arms opposite ends, said support member being fixedly attached to said bars to move therewith.
 13. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame, and a surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool enclosure, a rotatable surface engaging maintenance tool and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a lift assembly for mounting the maintenance unit on the main frame and selectively moving the maintenance unit between a lowered first position in which said tool engages said surface and an elevated second position in which said tool is substantially spaced from said surface, said lift assembly including a parallel linkage assembly mounted on the main frame and having a support member movable between a position in which said tool engages said surface and a tool elevated position, operator controlled means for moving said parallel linkage assembly, and second means mounted on the support member to move therewith for mounting the surface maintenance unit for movement with the support member and pivotal movement relative thereto, the second means including a generally horizontal pivot member having a generally horizontal pivot axis and third means for mounting said pivot member on the support member for movement between a datum first position and a second position, the surface maintenance unit including means for mounting the housing on said pivot member for pivotal movement about said horizontal axis, said housing being mounted on said pivot member for angular movement through an angle of about 90* between a datum position in which the tool extends downwardly of the housing and a second position in which the tool extends laterally outwardly of the housing, and said third means being of a horizontal length to, in the pivot member second position, position the housing in the housing second position so that the said tool is engageable with a vertical surface as the power unit moves forwardly parallel to said vertical surface and adjacent thereto.
 14. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame, and a surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool enclosure, a rotatable surface engaging maintenance tool and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a lift assembly for mounting the maintenance unit on the main frame and selectively moving the maintenance unit between a lowered first position in which said tool engages said surface and an elevated second position in which said tool is substantially spaced from said surface, said lift assembly including a parallel linkage assembly mounted on the main frame and having a support member movable between a position in which tool engages said surface and a tool elevated position, operator controlled means for moving said parallel Linkage assembly, second means mounted on the support member to move therewith for mounting the surface maintenance unit for movement with the support member and pivotal movement relative thereto, said second means comprising a pivot member having a pivot axis extending generally longitudinally in the direction of normal movement of the machine, said pivot member being mounted on the support member, and means for mounting the surface maintenance unit on the pivot member for pivotal movement about said axis through a substantial angle from a predominantly horizontal position to a predominantly vertical position and cooperating means on the power unit and the surface maintenance unit for releasably retaining the surface maintenance unit in said vertical position.
 15. The apparatus of claim 14 further characterized in that the surface maintenance unit in a horizontal position has a substantially greater transverse width than the minimum transverse width of the main frame and a height substantially less than its transverse width.
 16. The apparatus of claim 15 further characterized in that the housing has transversely spaced first and second side walls that in part define said enclosure, that the pivot member is located substantially transversely more closely adjacent the first side wall than the second side wall when the surface maintenance unit is in a horizontal position, and that the surface maintenance unit includes third means mounted on the housing for cooperating with the parallel linkage assembly for releasably retaining the housing in a predominantly horizontal position.
 17. The apparatus of claim 16 further characterized in that the surface maintenance unit in a horizontal position has a center of gravity that in a transverse direction is located between said pivot axis and the second side wall and more closely adjacent the pivot axis than the second wall.
 18. The apparatus of claim 17 further characterized in that the housing includes a frame member, that the third means includes a control member mounted on the frame member for pivotal movement about a second pivot axis between a first position engaging the support member to retain the surface maintenance unit in a predominantly horizontal position and a second position permitting the surface maintenance unit being rotated about the first pivot axis through an angle of about 90*, and slidably movement relative the frame member along said second pivot axis and resilient means acting against the control member to resiliently urge the control member to a slidable position that the control member in its first pivotal position abuts against the support member.
 19. The apparatus of claim 18 further characterized in that said surface maintenance unit includes a debris hopper, that said housing has a top hopper insert opening and means for slidably receiving said hopper when inserted through said top opening and supporting said hopper in a position to receive material raised by said tool, said enclosure having an opening for material raised by said tool moving into said hopper, and that said control member has an arm for abutting against the hopper to block the hopper from moving out of the top opening when said element is in its second pivot position and has been slidably moved by said resilient means, even when the surface maintenance unit is moved to its vertical position.
 20. The apparatus of claim 18 further characterized in that the power unit includes lock means mounted on the main frame for selectively releasably retaining the linkage assembly in a position in which the surface maintenance unit is in a sufficiently elevated position to be turned from the predominantly horizontal to the vertical position.
 21. The apparatus of claim 20 further characterized in that the last mentioned lock means includes a lock plate having a first portion abuttable against the linkage assembly to retain it in a position to support the maintenance unit at an elevation in which it is able to be turned to a veRtical position and a second portion abuttable against the linkage assembly to retain it in a position in which the maintenance unit is at an elevation such that the tool is vertically spaced from said surface and lower than that elevation at which the maintenance unit may be turned to its vertical position, and means for selectively moving the lock plate between a position out of the path of movement of the linkage assembly and a position in which the linkage assembly abuts against the desired one of said plate portions, that the means for moving said linkage assembly includes power means for selectively moving the parallel linkage assembly between said tool positions and that there is provided power means for driving said tool.
 22. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame and a power driven surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool enclosure, a rotatable surface engaging maintenance tool, and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a power operated lift assembly for mounting the maintenance unit on the main frame and selectively moving the maintenance unit between a lowered first position in which said tool engages said surface and an elevated second position in which said tool is substantially spaced from said surface, said lift assembly including a support member, first means for mounting the maintenance unit on the support member for movement therewith, a linkage device attached to the support member for moving the support member therewith and mounted on the main frame for movement between the maintenance unit first and second positions, power means for moving said linkage device between the above positions, and latch means mounted on the frame for movement between a first position for retaining the linkage device in the maintenance unit tool elevated position and a second position out of the path of movement of the linkage device, and second means for selectively moving the latch means between its positions, said latch means comprising a latch plate pivotally mounted on the main frame, said latch plate having a camming edge abuttable against said linkage device for pivoting the latch plate out of its path of movement as the linkage device moves from the maintenance unit tool surface engaging position to the maintenance unit tool elevated position, and said second means including resilient means for resiliently urging the latch plate to pivot to the latch means first position and operable means for pivoting the latch plate to the latch means second position.
 23. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame and a power driven surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool enclosure, a rotatable surface engaging maintenance tool, and first means for rotatably mounting said tool on the housing to extend within said enclosure, said power unit including a power operated lift assembly for mounting the maintenance unit on the main frame and selectively moving the maintenance unit between a lowered first position in which said tool engages said surface and an elevated second position in which said tool is substantially spaced from said surface, said lift assembly including a support member, first means for mounting the maintenance unit on the support member for movement therewith, a linkage device attached to the support member for moving the support member therewith and mounted on the main frame for movement between the maintenance unit first and second positions, power means for moving said linkage device betwEen the above positions, and latch means mounted on the frame for movement between a first position for retaining the linkage device in the tool elevated position and a second position out of the path of movement of the linkage device, and second means for selectively moving the latch means between its positions, said first means including a pivot member mounted on the support member to move therewith and having an axis extending predominantly longitudinally in the direction of normal movement of the machine, and means for mounting the maintenance unit on the pivot member for pivotal movement about said axis between a position extending predominantly horizontally and a position extending predominantly vertically, said maintenance unit in its horizontal position having a transverse width substantially greater than the maximum transverse width of the power unit and a maximum height substantially less than its transverse width.
 24. The apparatus of claim 23 further characterized in that said linkage device in the tool first elevated position supports said support member at an elevation that in attempting to turn maintenance unit from the horizontal position to the vertical position, the maintenance unit engages said surface to block further turning movement toward the vertical position, and that said linkage device is movable by the power means to a third position in which the support member is at an elevation that the maintenance device can be freely turned between horizontal and vertical positions.
 25. The apparatus of claim 24 first characterized in that the latch means has a first portion for supporting the linkage device in said maintenance unit first position and a second portion for supporting the linkage device in said third position, said second means including means for selectively moving the latch means from its second position to its first position to have the selected one of the latch means first portion and second portion support said linkage device.
 26. The apparatus of claim 24 further characterized in that there is provided cooperating means on the lift assembly and the maintenance unit for selectively retaining the maintenance unit in each of its horizontal and vertical positions, that said linkage device includes upper and lower parallel arms pivotally mounted on the main frame, and that the first means comprises a vertical bar pivotally connected to said parallel arms and means for attaching the support member to the vertical bar in a fixed position relative thereto.
 27. The apparatus of claim 24 further characterized in that the support member comprises a member that is elongated in a direction transverse to the direction of normal longitudinal movement of the machine and mounted by the linkage device for movement therewith and means for mounting the pivot member on the support member for transverse movement relative thereto between a datum first position and a second position substantially transversely offset from the datum first position, the pivot member in its datum position with the maintenance unit in its horizontal position being located to substantially transversely center the maintenance unit relative the power unit so that upon turning the maintenance unit to its vertical position, the tool is transversely inwardly of the adjacent side of the power unit, and the pivot member in its second position being sufficiently transversely offset from the datum position to position said maintenance unit in its vertical position so that the tool extends transversely outwardly of the power unit adjacent side to permit the tool engaging a generally vertical surface as the power unit moves generally longitudinally forwardly.
 28. A maintenance machine for surfaces such as a floor or the like and that usually is driven in a longitudinal forward direction, comprising a power unit having a main frame and a power driven surface engaging wheel assembly mounted on the main frame, and a surface maintenance unit that includes a housing having a downwardly opening rotary maintenance tool enclosure, a rotatable surface engaging maintenance tool, first means for rotatably mounting said tool on the housing to extend within said enclosure, a second rotatable surface engaging tool, second means for rotatably mounting said second tool in the enclosure, said housing including side walls, a front wall and a deflector above the tools that are joined together to form said enclosure, a hopper having a debris receiving opening and a top wall, means for mounting the hopper on the housing to receive material raised by said tools, said hopper mounting means mounting the hopper for withdrawal from the housing, and including a transverse panel joined to said deflector to extend thereabove and joined to said side walls, and closure means mounted by one of the side walls, deflector and front wall to in cooperation with the side walls, deflector and panel form a second enclosed chamber, said housing having an enclosure opening for material raised by said tool moving out of the enclosure into the hopper, said first and second means including drivable means for driving said tools, motor means mounted in said second chamber and having a drive shaft extending outwardly of said second chamber and means for drivably connecting said shaft to the drivable means, said tools being tubular tools having transverse axes of rotation and tubular cores, said first and second means each including an idler plug mounted on a side wall to extend therethrough and for withdrawal from the exterior of the side wall on which it is mounted, each idler plug having a tool mounting portion slidably extended into the respective core, an intermediate portion of a substantially smaller longitudinal cross-sectional area perpendicular to the axis of rotation of the core than the cross-sectional area of the core interior that is perpendicular to the axis of rotation of the core, the intermediate portion being extended through the side wall on which the idler plug is mounted and forming a close fit therewith, and a portion of a substantially larger longitudinal cross-sectional area than the corresponding cross-sectional area of the intermediate portion that is located exterior of the enclosure and removably secured to the last mentioned side wall, each of said tools having a hub mounted within the core for slidably receiving the respective tool mounting portion whereby the hub is rotatably mounted on the tool mounting portion, and said power unit including a power operated lift assembly for mounting the maintenance unit on the main frame and selectively moving the maintenance unit between a lowered first position in which said tools engage said surface and an elevated second position in which said tools are substantially spaced from said surface. 